Am I able to swap carbs on a stock 327 intake,or do I need to swap that as well? Swap from quad jet to pro form carb. Issues with car wanting to stall under throttle. Any advice? Sorry if it's a noob question. Learning as I go
You have to use adapter plate to use square bore carburetor you can get them at o riellys Posted using the Full Custom H.A.M.B. App!
DON'T use the adapter!!! If you are going to make the swap, do it right. Buy a square-bore intake. Why??? The Q-Jet you have is a 750 CFM. That figures 150 on the primary side, and 600 variable on the secondary side. The manifold is configured the same way. Now, let's guess that you are thinking of a 750 Pro Form square-bore carb. They are basically 375 CFM on both sides. Now what happens if you use the adapter and the wrong manifold??? You get 150 CFM on the primary side, and 375 CFM on the secondary side for a TOTAL of 525 CFM!!! And for your issues with the engine wanting to stall under throttle, check your accelerator pump function. Jon.
Ok. As soon as it warms up here in the arctic, I mean Michigan I will look at the carb, I'd rather make do with what I got anyhow
It is my impression that a Quadrajey, in good operating condition, properly jetted and adjusted, is one of the better, if not best, 4 bbl for street use. At low speed/rpm you get good throttle response and economy,.....under load it provides plenty of fuel and CFM.
For a "bone stock" 327, 750 CFM sounds too big for normal street use, 600 CFM might be better. If there is no black smoke, stalling is often an indication of a lean condition, too much air or not enough fuel in the air/fuel mixture. But engine temperature and ignition timing must also be considered. If your Quadrajet is clean and working right it should be plenty good enough.
IMO, Quadrajets are one of the most misunderstood and underrated carbs out there. They are a very good choice for a mild street engine and the small primaries and big secondaries can give really good gas mileage and performance when you open it up. There are a million small block and big block Chevy marine engines running around with them, so they must not have been all that bad. If I were you, I would consider rebuilding or having yours rebuilt. There isn't much to them when you tear them apart. Don
I currently run a Q-jet on a 327 (for 25 years), a Holley 650 spreadbore on a 283 (for 40 years) and an Eldebrock (AFB) on a 383 (for 6 years). My least favorite is the Q-jet. No parts to tune like the other two. The Holley needs care and feeding by a carb hobbiest (me) and the Eldebrock is a minor problem in the cold weather with the electric choke. Take your pick. If you run a carburator be ready to work out the kinks on any combination. The manifold choice will improve the performance but the carb will not perform well with any of them if not set up correctly.
To my understanding the carb was rebuilt professionally according to the fella I got the car from, it looks damn near new, I'm not very savvy when it comes to adjusting carbs. Any good links that could point me in the right direction? I love to dive in, but don't want to make it worse!
Didn't know that about the Q-jet manifold, I learn somthing everytime I come on here. I must confess, Iv'e never had much luck rebuilding carburators, I just buy a 'new' one and be done with it.
I wouldn't adapt a square bore carb to a Quadrajet intake either. Used intakes for SBCs are so cheap that you can probably pick one up for the price of a new adapter anyway.
I agree that a quadrajet set up right is a pretty nice carb for a stock motor . Are your sure your timing is set right ? That can cause a lot of issues too.
Also I'm sure if you type in your carb on a google video search there will be a how to set up video . Holly has them on there website too .
Before spending anytime shopping for a intake carb combination, do a full tune up. You most likely will have to do it anyway once you find out the carb wasn't the problem. If you are unsure about any part of the tune up, go get it done by some one that does know. The Q-jet was one of the best carb made. Joe
I was told that the carb was rebuilt, but never set for the car. But I am going to do a tune up in the spring, if it ever gets here. Been working on suspension, guess I should make her run better first!
Look for this number on the left rear of the carb and let us know what it is. This will tell us the calibration and would be helpful to know. The distributor type and number would be too.
I used to run a Quadrajet and it was great. I switched to an Edelbrock for the looks. The Edelbrock is a good carb, but it wasn't as good as the Quadrajet.
The two normal adjustments on the Q-jet won't effect the problems you are having if the internals are working proper in the carburetor. Idle speed is simple enough, one screw on the left side holding the linkage open. The other adjustment is idle mixture, two screws in the front on the base plate, one each side facing the cabin of the car. 1 1/2 turns out from seated is about right for most. Adjust when the engine is warm, turn in till the engine stumbles and back till it smooths out ( stay in the 1 1/2 - 2 turn range). Do each side a couple of times till you are sure each one is the same. You will have to readjust idle speed and mixture when you get the timing set. It all works together so keep going back and forth at each adjustment fine tuning them. Joe
The most common problems with WOT stalling are: Plugged fuel filter Leaking Vacuum break letting secondary flop open;
It's not a WOT problem, it happens as soon as I hit the pedal. I really have to apply fuel very slowly.
I will try and get the carb numbers. It's a little difficult to get at right now. She's tucked away for the winter, which doesn't seem to want to end.
I have the same problem on a fresh rebuild. It only happens when I first get moving and after that I am fine. I need to tune mine a bit more I am running a 2gc on a 283 but I imagine it could possibly be the same issue. Things improved with new plugs. There is lots of content out there. I can link some books that helped me out a lot if you'd like.
Look down the throat, you should see 2 strong steams of fuel when you open the throttle. If not the accel pump ck ball could be missing or not seated.
Is it the original carb? Reason why i'm asking is because (w/o knowing anything else) My friend had a similar sounding problem and it was an over carbed sbc and a single plane intake. But, I agree with Joe. tune up first.
I have delt with q jets and have run into nothing but problems with them unless they're new and even then I had a problem. just go and get yourself a 600 Holley carburetor electric choke vacuum secondarys. You can tune them easily and it will be plenty of Carb and get the right intake. Also don't get the adapter for a Carb it just isn't right. Hope this helps. Posted using the Full Custom H.A.M.B. App!
Stumbling, like you describe, can be lots of things. Your vacuum advance may be not working right, you may have a sloppy timing chain, or your accelerator pump might not be shooting enough fuel in there. Do like was suggested, look down the throat of the carb when the motor is not running and move the linkage, you should see a couple of strong streams. For the timing issue, put a light on it and see how smoothly the spark advances. The advance on the timing mark should be smooth and steady, not ragged. Advance the distributor until it cranks slowly then back off just a tad until it will crank fast. That will put you in the ballpark of getting the timing advanced as far as you can and might help find what is going on. I had one years ago that I chased and it turned out to be sloppy bushings in the distributor. A reman distributor cleared it right up. Not saying that is your problem, but consider more than the carb in your diagnosis. Don
They are pretty cheap used too: http://www.amazon.com/gp/aw/d/0895863014 http://www.amazon.com/gp/aw/d/1932494189 You might want to pick up a vacuum gauge if you don't have one. Also pretty cheap and invaluable when tuning
The Jalopy Journal
